Sciencemadness Discussion Board - The Smell of Iron, Copper

The Smell of Iron, Copper

chemoleo - 22-4-2006 at 18:47

Today I dealt with an iron sulphate solution, and was immediately struck with the strong smell of it. It sticks to my fingers, almost pollutes the whole room, even though I only touched a few dry iron sulphate crystals. Hand washing makes no difference, the smell is still there, if not stronger. I am trying to remember if blood smells like that, and I think, to some extent it does.
Interstingly, I remember from handling copper sulphate, that it has a similar smell, albeit by far not as intense.
Now, I could rationalise the taste of it, even tiny quantities, but smell? What makes the iron so volatile that it can be smelled?
It seems quite paradoxical, since FeSO4 is a nice solid, and ionic, so it won't produce any noteworthy gaseous quantities.

What produces the smell? Guesses, input anyone?

zoomer - 22-4-2006 at 19:09

You may have inhaled small particles as dust, which have now lodged in your nasal passages. It sounds like the compund may have some affinity for bonding to tissues if you can still smell it on your fingers. You may also be a person who is particularly sensitive to the smell. To me copper sulphate has no smell, and iron sulphate only barely so, and my sense of smell is otherwise normal as far as I can tell.

Z

chemoleo - 22-4-2006 at 19:14

Yes, I agree that this may well be the case, thanks for pointing this out. However, the smell is distance-related, the further away the less intense. My fingers actually smell less by now.

Anyway, I was more after why a non-volatile compound such as FeSO4 could be smelled in the first place. Have a sniff at a solution of it. But then, I suppose you could argue that aerosols are generated, which can be smelled....lets see if the FeSO4 tube smells after not having it disturbed it for a while.

Mr. Wizard - 22-4-2006 at 21:34

Iron has a very noticeable smell to me as well. There is often a metallic taste as well, no surprise there. Iron -sulfur compounds are very strong. Even regular rust and iron filings or grindings have a smell too. After spreading an iron garden supplement the smell is overpowering, and even seems to accelerate body odor. The area where I live has very alkaline soil due to calcium carbonate in the water, so iron has to be added to many plants. There is a chelated iron compound that works well, and after adding it to water it smells just like blood, and is a very red color. It is always the last thing to do, just before heading to the shower.

I have not noticed as much smell with copper compounds, although there is some sort of acrid taste to many of them. I developed a very sore throat after handling a very small amount of cupric acetate. I realized it was a fine powder and thought I was being careful. I'll be much more careful in the future.

Chris The Great - 22-4-2006 at 21:40

Sorta on this topic, you ever notice metal has a slight smell as well? I'd like to know why that smells, as well as why some compounds smell as well.

12AX7 - 22-4-2006 at 22:41

I've noticed that iron, copper, and probably nickel have smells. It doesn't work for clean metal though- I think it has to have been touched, which may suggest it's catalyzing a reaction with something in the fingerprint or dead skin or whatever.

After sanding copper and handling it with bare hands, I smell nothing. Immediately on handing pre-touched copper, I smell the distinctive odor.

U.S. nickels (75% Cu, 25% Ni) I think have a somewhat sweeter metallic smell, which may suggest nickel has a somewhat different odor.

My CuSO4 and FeSO4 don't smell, at least I don't remember the iron smelling, but as pure crystalline compounds I would hope they don't. After say, soaking your hands in solution or fine crystals and your own sweat, I can imagine lots of stuff would happen.

Tim

darkflame89 - 22-4-2006 at 23:46

Hmm, I have noticed this smell too while handling copper(II) acetate. At first I thought the smell was due to the vinegar smell, but on comparing a vinegar solution and the copper(II) acetate, the Cu(Ac)2 stands out with a distinct metallic smell not quite unlike that of iron, as pointed out by Chemoleo. After sniffing on this stuff for a while, you can get dizzy, and I've noticed that after that, my sense of smell for other stuff is sort of deadened for a day or more.

garage chemist - 23-4-2006 at 01:37

I have noticed this too with iron sulfate, although not as intense as you describe.
I can think of two explanations for this, except from the possibility of particles (which doesn't explain that your fingers smelled).

One: Iron, when it contains carbon, forms (along with the usual cementite) a special sort of carbide in which the carbon atoms exist as chains. If the iron is dissolved in an acid, this carbide hydrolyzes into a mixture of gaseous, liquid and solid hydrocarbons. I have read this in a big chemistry book, the Hollemann- Wiberg.
Ever noticed how there is a really strong smell when you dissolve steel wool in dilute HCl or H2SO4? It cold be due to those hydrocarbons.
And the carbide can also slowly hydrolyze with aerial moisture, which explains the smell of metallic iron.
Iron sulfate might simply be contaminated with those smelly hydrocarbons.
I'd be interested if totally carbon- free iron also smells when dissolved in HCl or H2SO4.

The second theory: Iron might (in very small traces) form a volatile tetroxide, just like Osmium. This must have an extremely powerful smell, if modern chemistry has until now failed to prove its existence.

Eclectic - 23-4-2006 at 03:55

Maybe carbonyls? Many metals form volatile compounds with carbon monoxide. Diketone complexes with metals can also be volatile.

[Edited on 23-4-2006 by Eclectic]

chromium - 23-4-2006 at 04:26

Common metals contain always some quantities of sulfur, phosphorus and arsenic. Although quantities are usually very small , these substances can make very smelling compounds. This is at least one of reasons why metal stinks when reacted with acids but maybe certain compounds of those non-metals are also cause of generic metallic smell?

[Edited on 23-4-2006 by chromium]

chemoleo - 23-4-2006 at 06:08

Thanks for all the interesting replies, and ideas.
I checked the FeSO4 solution that I prepared yesterday, and the smell is gone, even if my nose is like 2 cm above the liquid surface.
So FeSO4 on its own isn't volatile (doh!), and the smell becomes intense once I shake the solution, and have a sniff again. Aerosols? Clumsy me got a drop or two onto my fingers again, and now they reek like crazy! So not aerosols. Conflicting evidence. Hmmmm.
Sniffing the analytical grade FeSO4*7H2O container (dry), the smell of iron is definitely there, albeit weaker.

Yes, I also noticed, the metals themselves smell, like 12AX mentioned.

I find it peculiar that noone tried to work this out. Potentially it has some interesting outcome...particularly if they are volatile products of iron!

unionised - 23-4-2006 at 07:02

Interesting question, and one I have wondered about before. Google didn't give me an answer.
The smell from disolving metals in acid is, as has been said, mainly due to things like AsH3, PH3 etc formed by nascent hydrogen reducing impurities in the metal.
The metal salts themselves, like CuSO4 and FeSO4 don't smell- hardly suprising because they are involatile.
On the other hand (Forgive the pun) when they come into contact with skin they do produce an odour. The same smell is produced by handling Cu coins etc.
I can only presume that either
Cu and Fe produce volatile salts with some component of skin or
They catalyse some reaction involving some component(s) of sweat and air to give a compound with a characteristic smell.
My guess would be the second option because volatile salts are rather rare. (and also because Cu (II) and Fe(III) both have oxidising properties so it's reasonable that they both form the same product and thus pretty much the same odour.)

I guess the next stage involves skin, FeSO4, and a mass spectrometer. I can provide the FeSO4, can anyone else help with the other items? :-)

Mr. Wizard - 23-4-2006 at 14:29

Speaking of coins, if anyone remembers when they had silver in coins, the US 90Ag/10Cu coins had a distinctive 'silver smell', which I always thought was from the sulfide. Even silver spoons and other silver had the same smell.

I am quite sensitive to the smell of ferrous ion

chloric1 - 23-4-2006 at 16:31

I have worked with ferrous sulfate in my lab and I notice the ferrungous odor quite easily. My baby daughter was anemic a few months ago and the doctor prescribed ferrous sulfate drops. The drops had the pale green color and smelled even stronger than my technical grade ferrous sulfate. My daughters ferrous sulfate had glucose or some other sugar to help with taste. Maybe there is a carbohydrate reaction with the iron through perspiration.

praseodym - 24-4-2006 at 20:17

Hmm, sulphate esters?

pyrochem - 24-4-2006 at 21:03

I haven't noticed a smell from copper or its compounds, but iron has a strong smell. Also, you can taste iron in juice that has sat in steel cans for a few days and in some molasses (the label claims it contains 20% of the daily value for iron, almost certainly as Fe(III)).

I have also noticed a smell with aluminum. Interestingly, indium smells like aluminum, only stronger. It is very soft, and after handling it, I noticed a metallic tinge on my fingers. Perhaps the metal flakes become airborne and react with water or acids in the nose to form ions.

DrP - 25-4-2006 at 05:27

I can smell copper coins - might be my imagination but I think they smell more when wet (??) and or dirtier.

woelen - 25-4-2006 at 06:54

The effect of copper smelling is quite common to me as well. If I handle copper coins, but also other copper objects, then I notice a certain smell. The same is true, when I bring my finger in contact with copper salts. With metallic copper, I only notice the smell, when the copper object is oxidized. A brand new 5 eurocents coin does not give any smell to me.
With iron (rust, metal, ferrous and ferric salts) I have a similar thing. The smell, however, is quite different to me, compared with the smell of copper.
With silver, I also notice a smell, again, different from copper and iron.
With nickel, I do not notice any smell, nor do I with gold, bismuth, zinc, and aluminium.

I think that the smell is due to reaction of the skin (or some of the solutions in the cells, sweat, etc.) with the metal ions, not with the metal itself. That explains, why clean copper does not provide the smell, while oxidized (dark brown) copper and also its salts do give a smell on my hands. The smelly compound probably is some organic compound, which, however, is different for copper, silver and iron.

The_Davster - 24-5-2006 at 17:13

I was working with some cerium today, now that smells horrible after you touch it. I have noticed the iron smell, but no other metals had a smell to them previously, however cerium...terrible stuff...

Neutrino, I remember that thread as well, and was also unable to find it.

Organikum - 24-5-2006 at 18:49

Quote:

Originally posted by chemoleo
Today I dealt with an iron sulphate solution, and was immediately struck with the strong smell of it. It sticks to my fingers, almost pollutes the whole room, even though I only touched a few dry iron sulphate crystals. Hand washing makes no difference, the smell is still there, if not stronger. I am trying to remember if blood smells like that, and I think, to some extent it does.
Interstingly, I remember from handling copper sulphate, that it has a similar smell, albeit by far not as intense.
Now, I could rationalise the taste of it, even tiny quantities, but smell? What makes the iron so volatile that it can be smelled?
It seems quite paradoxical, since FeSO4 is a nice solid, and ionic, so it won't produce any noteworthy gaseous quantities.

What produces the smell? Guesses, input anyone?

I think you have contracted an incurable disease and you must die. Sorry.

it´s called "stinky fingers" btw.

[Edited on 25-5-2006 by Organikum]

triphenylphosphineoxide - 25-5-2006 at 06:48

The strongest source of this smell that I know is the creek that runs past my house.
The soil around here is highly acidic, lots of soluble aluminium and the creek runs through a rich patch of iorn pyrite. The iorn pyrite in distilled water or dissolved in HCl does not smell as stongly as the creek or fingers after spilling the acidified solution on them.
I definately favour the theories put forward by chloric1, woelen and unionised.

Nerro - 25-5-2006 at 07:09

A while back I was at a theater where I sat on the balcony, the balcony had copper rails and the rails had very typical smell reminiscent of ozone... Any theories on that?

Canuck - 27-5-2006 at 22:56

Copper oxides/nitrides have the smell you are describing. I recently went to pick up a batch of black copper oxide for a large target and noticed the pungent smell right away.

interesting stuff.

12AX7 - 28-5-2006 at 04:38

My copper oxide doesn't smell, but then I pyrolyzed it (as part of the production), too.

Tim

Eclectic - 19-10-2006 at 04:43

This seems to be the answer:

http://www.sciencedaily.com/releases/2006/10/061018150716.ht...

woelen - 19-10-2006 at 09:24

This answer, however, is very specific for iron, it cannot explain the smell of copper, cerium, and some other metals. These metals have different smells, so should their mode of operation also be different, when it comes to making smelly organics.

stricnine - 19-10-2006 at 11:23

I also can smell and taste iron, e.g. when polishing a rusted iron blade. After washing all the stuff (and even drying the blade), I can still smell the iron if I get the blade close to my nose.

12AX7 - 19-10-2006 at 15:14

Reminds me, I've noticed when using my hand-forged steel knife (made of automotive coil springs, probably 5160 (chrome steel)), I get a weird almost skunky odor (probably thio-based, eh?) when cutting most fruits, in addition to the metallic odor of bare non-stainless steel.

Tim

[Edited on 10-19-2006 by 12AX7]

kmno4 - 31-10-2006 at 14:14

It is interesting question: smell of iron. Whenever I work with Fe(II) salts - known odour..... . Human blood has also such smell, and because of great molecular weight of hemoglobine, I think that it is not any vapours containing Fe. It seems to me thai it may be caused by "free radicals", whatever it means

. Propably this smell exists only when Fe(II) oxidates itself to Fe(III) <--- which is odourless (as they say - and it seems to be true to me). Water is also very important - dry salts propably do not smell. And in the end - "skin oil" has nothing to it.
These are my considerations, they do not have to be true

unionised - 1-11-2006 at 11:19

"And in the end - "skin oil" has nothing to it."

Sure about that?

"http://www.newscientist.com/channel/being-human/mg19225754.400-ancient-human-hunters-smelt-blood-on-the-breeze.html"

zoomer - 1-11-2006 at 19:18

And if evolution has enabled us to smell the iron in blood, and everyone recognizes the smell of iron as distinctive, why is the taste of blood universally described as "coppery"? (While there is some copper in blood, it is orders of magnitude less than iron.)

Z

DrP - 2-11-2006 at 02:55

Quote:

Originally posted by zoomer
And if evolution has enabled us to smell the iron in blood, and everyone recognizes the smell of iron as distinctive, why is the taste of blood universally described as "coppery"? (While there is some copper in blood, it is orders of magnitude less than iron.)

Z

I've seen it described more as 'metailic' in general rather than 'coppery'

IPN - 2-11-2006 at 05:46

This seems to be a more general answer to the question.

http://www.rsc.org/chemistryworld/News/2006/October/25100601...

Mr. Wizard - 2-11-2006 at 06:50

The link would explain why iron seems to increase body odor.

Another metal that I can smell is Silver, or more precisely, dirty Silver, such as coins, electronics, or silverware. I'm sure it has something to do with Sulfides on the surface of the metal. I can sniff a coin or wire, especially if it is in a container and tell if it's got a silver surface. No big trick, for sure. Has anyone else noticed it?

Jdurg - 2-11-2006 at 07:32

Quote:

Originally posted by DrP

Quote:

I've seen it described more as 'metailic' in general rather than 'coppery'

You can say that again.

I've always thought of the taste as quite rusty which is somewhat true.

unionised - 2-11-2006 at 11:17

"It is not every project that can answer an everyday riddle like why do metals smell,’ said Andrea Dietrich, an environmental chemist and part of the team at Virginia Tech, Blacksburg, US. ‘The surprise is that the odor was associated with organic molecules and not inorganic metals,’ she told Chemistry World."
I'm glad someone seems to have done essentially the experiment I proposed earlier in this thread. I don't understand why they are suprised that the odourous material was organic most metal compunds are involatile. Still whatever suprises who, it's nice to hope that this might get used diagnosticly.

The_Davster - 6-11-2006 at 22:04

Has anyone else noticed that some people smell distinctly metallic? This girl who sits next to me in one of my lectures has breath that reeks of metal, like iron. The smell even leaves a metallic taste in your mouth it is so powerfull. It seems most similar to iron.

I wonder if it indicates some underlying medical condition or something.

12AX7 - 7-11-2006 at 09:04

Could be. One day I noticed my friend had breath that smelled *exactly* like aluminum slag, which smells due to a combination of impurities such as sulfides, phosphides, etc., hydrolyzed by moisture.

Tim

Mr. Wizard - 7-11-2006 at 09:44

12AX7, did your friend have some heavy duty garlic the day before? I've noticed certain combinations of food, such as garlic sauted shrimp, and wine, seem to give people a toxic breath that defies description. The 'owner' of the toxic breath seems unaware that his breath could strip paint and discolor the silverware

Is this the phosphine breath you are talking about?

Nerro - 7-11-2006 at 10:23

Quote:

Originally posted by Mr. Wizard
12AX7, did your friend have some heavy duty garlic the day before? I've noticed certain combinations of food, such as garlic sauted shrimp, and wine, seem to give people a toxic breath that defies description. The 'owner' of the toxic breath seems unaware that his breath could strip paint and discolor the silverware

Is this the phosphine breath you are talking about?

Which is why France ought to be bombed

Some people have acetone in their breath because they have [that illness when you can't eat sugar without injecting yourself with insulin all the time...], might it be possible that some other defects cause one to exhale different metabolic products that have distinctly metallic smells? The article mentions small organic molecules like aldehydes and ketones etc. During metabolism (both yours and that off the stuff that lives inside you) these are often formed, perhaps they are the cause of the "metallic breath".

Alternatively maybe she just has a "diverse" diet like 12AX7 said.

I've also heard that people who have pneumonia have chlorine in their breath. Anyone ever smell that coming of their girlfriend?

unionised - 7-11-2006 at 10:59

I think it's more likely that anyone breathing chlorine would get pneumonia.

Nerro - 7-11-2006 at 12:06

small quantities obviously (you funny funny little man...)

12AX7 - 7-11-2006 at 13:22

No idea what he ate earlier that day (or the day before).

Insulin is used for diabetes.

BTW, garlic pwns j00. :cool:

Tim

Edit: WTF? The smileys disappeared from the "Post reply" or "edit" page (they're still on the quick reply window)!

[Edited on 11-7-2006 by 12AX7]

Nerro - 7-11-2006 at 13:52

We let the novices eat garlic during initiation

(EAT! THE! FKN! GARLIC! NOWWWWW! It's good for you, see, we're taking care of you. Why don't you thank us?)

And, yes, diabetes was the word I was looking for. Could it be possible that some type of bacteria in your mouth excrete "metallic smelling" organic compounds?

chloric1 - 7-11-2006 at 15:22

Quote:

Originally posted by The_Davster
Has anyone else noticed that some people smell distinctly metallic? This girl who sits next to me in one of my lectures has breath that reeks of metal, like iron. The smell even leaves a metallic taste in your mouth it is so powerfull. It seems most similar to iron.

I wonder if it indicates some underlying medical condition or something.

The iron smell could be caused by excess iron suppliments. Women are encouraged to dose up on iron during menstral cycles. She could be overdoing it possibly damaging her liver???!!!

DrP - 8-11-2006 at 02:23

Quote:

Maybe she doesn't clean her teeth that often, or not very well. If she has slight gum disease then her gums could be bleeding slightly - thus the iron smell?

Mr. Wizard - 8-11-2006 at 09:14

Most people with bleeding gums have periodontal disease or 'rotten gums', and their breath smells more like decaying meat than metal or iron. Various amines, including putrescine and cadaverine contribute to the smell. The smell can come from trapped food and bacterial pockets beneath the gum line. Metal doesn't have much to do with it. IMO

Ozone - 8-11-2006 at 18:21

Hello!

this just off-the-press:

Ritter, S. (2006). The Smell of Iron. C&E News, 84 (44), Oct. 30, pp. 12.

According to this, perspiration oxidizes Fe° to Fe 2+ which engages lipid peroxodation (probably via Fenton-type chemistry involving the OH radical). The products of this are responsible for the smell, for example, 1-octen-3-one, or, from pickled iron, methylphosphine (which is a "garlicky" one, for sure). The parent article is cited as:

Angew. Chem. Int. Ed. 2006, 45, 7006.

A most timely topic, indeed!

O3

[Edited on 9-11-2006 by Ozone]

unionised - 9-11-2006 at 11:19

Hardly hot off the press, It had made its way into new scientist magazine a week or so back.
Also, not a very timely topic as it has been going for ages.

Did you read the thread befor posting?

BTW, can anyone think of a plausible mechanism for the production of chlorine (even small ammounts) in the lungs?
I know that there's chloride there and that the immune system uses peroxy species as part of its arsenal, but I can't help thinking that any Cl2 produced would get trapped by all that organic stuff.

[Edited on 9-11-2006 by unionised]

Ozone - 9-11-2006 at 16:22

Whew, two weeks is not timely? Tough crowd, my apologies.

Yes, I did read the thread. The C&E news for that week arrived in my mail 4 days ago, where it sat until I could get to it. I thought there was relevance since very similar articles were carried in two venues within one week of one another (same scientists).

Anyway, I have the real article if you or anyone else is interested.

O3 out

Jdurg - 10-11-2006 at 08:15

It's also possible for people who consume alcoholic beverages frequently, or in great quantities, to have acetone like breath.

Random - 7-5-2011 at 03:03

This could cause the smell of metals:

http://en.wikipedia.org/wiki/Oct-1-en-3-one

cyanureeves - 7-5-2011 at 05:07

twice i have been with people that leave the whole room smelling like strong B complex vitamins.both times the persons color seemed yellowish. i thought the smell emitted from their breath but it also came from out their nostrils. i quickly thought of liver disease as in psorosis or hepatitis but medicines also can cause wierd smells and diabetes also cause liver and kidney damage. hygiene had not much to do with it but it didnt matter because i still reacted as if they had the plague.

I Like Dots - 24-12-2013 at 15:36

Tonight I grabbed my dehydrated copper sulfate to color the camp fire. It was stored in a plastic water bottle. When I opened it, I was greeted with a very strange smell, reminiscent of a organic solvent, but I can't put my thumb on it.

could the copper sulfate have reacted with the water bottle?

edit- I remember pouring the Copper Sulfate in the bottle when it was still hot.

[Edited on 25-12-2013 by I Like Dots]

Poppy - 29-12-2013 at 09:02

As far as I have supposed it is the iron itself that contains free sulfurous or phosphorous particles that grant this smell. The particles are then dispersed and hardly separable when metallic iron is dissolve. As a sample, shiny bars of iron had been cleaned free from rust by immersing in a citric/ benzoic acid aqueous solution and then washed with lime water, the shiny iron smelled just as solutions of iron sulphate, and on accounting for the washes its not likely that the organic compounds played a significant role with it.

Random - 29-12-2013 at 09:18

Actually Poppy, it's not that iron has a smell but it's the smell of our lipid peroxides which react with Fe ions.

Poppy - 29-12-2013 at 16:50

But, how simple is it, it just has been told, what if no bare hand had touched the iron piece at all?

Random - 29-12-2013 at 16:55

It could be that there is contact with them over our breath, air-nose-metal etc.. It doesn't necessarily need a touch as the smell can be noticed in very small concentrations.

Now I'm talking about metallic taste and smell as in taste of blood, there are more of these metalic type smells. One could also be phosphorus and sulphur impurities too, especially rhis can be noticed when you dissolve iron nails in HCl there is smell of H2S.

[Edited on 30-12-2013 by Random]

TheChemiKid - 29-12-2013 at 17:27

I have a copper counter in my house, and it has a very characteristic smell.
I cannot describe it beyond metallic.

Eddygp - 18-2-2014 at 13:50

I have just found this thread so I will not open a new one. The thing is that I can very easily detect the smell of copper, particularly if I am rubbing a copper object with my fingers. Actually, when I inhale deeply with the object close to my nostrils, it is even uncomfortable. I have also noticed a different smell when I dissolve copper(II) sulfate in hot water. Just lean to the hot beaker and draw in some air and you'll get that smell. It is NOT the same smell. In fact, I believe that the latter one has something to do with the sulphur. Iron smell, copper smell, nickel smell, aluminium smell, zinc smell... they are not the same. I'm really intrigued.

Poppy - 20-2-2014 at 15:43

Okay tin smells particularly different IMO but the metallic smells are not quite distinctive.
Likewise keeping stuff on people's house certainly impregnates them with distinctive smells. Just figure a teen's room closed 24/7 while he/ she farts and eats pizza, disgusting. Pity for the old brass clock standing beside the couch.

Eddygp - 24-2-2014 at 09:24

Quote: Originally posted by Poppy

Okay tin smells particularly different IMO but the metallic smells are not quite distinctive.
Likewise keeping stuff on people's house certainly impregnates them with distinctive smells. Just figure a teen's room closed 24/7 while he/ she farts and eats pizza, disgusting. Pity for the old brass clock standing beside the couch.

The smell I mentioned is found on every copper object, regardless of the location. Iron objects brushed with steel wool to expose the metal also smell particularly strong.